Everything about the Sun is huge: temperatures, pressures, size and mass. Even though we know those fairly accurately, the Sun can still surprise. Last October the Sun sported AR 2192, the largest sunspot grouping in the last 24 years. This week the Sun exhibits one of the longest filaments ever recorded.

A filament is a portion of solar plasma that is suspended above the surface of the Sun by magnetic forces. Since it is being held above the surface it is slightly cooler making it appear darker. This one has been measured to be about 435,000 miles long. The Earth has a diameter of just under 8,000 miles and the distance from the Earth to the Moon is just under 239,000 miles. Those values put the length of the filament into perspective.

Right now, we view the filament from above. But as the Sun continues to rotate, the filament, if it survives long enough, will eventually be seen from the side. Once that happens the filament will become a prominence. A filament and a prominence are the same object, just viewed from different angles.

This image is a stack of 150 frames taken this afternoon through the PTO’s 60mm H-alpha telescope.